The monovalentplus concept Opel has used in its natural gas-powered vehicles (CNG = Compressed Natural Gas) since 2002 is unique on the market. Among its many advantages and benefits, this system boasts unrivalled operating costs, produces up to 80 percent lower emissions and 20 percent less CO2 than a comparable gasoline engine. It enables an operating range of up to 400 kilometers in natural gas mode and guarantees unrestricted passenger and luggage compartment use. Opel CNG vehicles feature a gasoline reserve tank that increases operating range by around 150 kilometers, ensuring full everyday suitability. The 1.6-liter natural gas engine is designed to run on natural gas, biogas, or any mixture of the two.

Opel Zafira ecoFLEX Turbo: Performance meets economics

For the first time, Opel has combined economical, low-emission Compressed Natural Gas propulsion with powerful turbocharger technology in the Zafira 1.6 CNG ecoFLEX Turbo. It is now available, starting at 25,430 euros, and allows Opel to ring in a new era of CNG with impressive performance. The new Zafira’s rated output of 150 hp and maximum torque of 210 Nm between 2 300 and 5 000 rpm ensure plenty of power in all situations. The high torque not only allows a more powerful drive, it also keeps energy consumption low in everyday use.

The seven-seater accelerates from 0 to 100 km/h in 11.5 seconds and has a top speed of 200 km/h. In the MVEG cycle, it consumes just 5.1 kg of natural gas per 100 km. This corresponds to a CO2 emission figure of just 139 g/km – a new best-in-class in this vehicle and power category. Expressed in terms of the driver and all six passengers, this translates into just under 20 grams per seat and kilometer when the Zafira is fully loaded.

Just like the Turbo, the new-edition Zafira 1.6 CNG ecoFLEX, which was launched in February 2008, also features the unique Flex7 seating system, which enables it to be transformed quickly from a seven to a two-seater without cumbersome seat removal. Thanks to the clever underfloor arrangement of the four natural gas tanks around the rear axle, the Zafira’s versatility and spaciousness remain unaltered. In its standard seating arrangement, the natural gas Zafira offers 645 liters of luggage compartment space – the largest of all seven-seat compact vans. The Zafira 1.6 CNG’s maximum load capacity is 1820 liters.

The Zafira 1.6 CNG ecoFLEX’s particular highlight is its outstanding efficiency. Average consumption of around 5.0 kg of natural gas per 100 kilometers, with an average H-gas price of 0.97 euros per kilogram (early 2009), translates into a fuel cost saving of around 30 percent compared to diesel, and over 50 percent compared to gasoline. Tax and insurance ratings are at the same level as those of a comparable gasoline variant. The

69 kW/94 hp natural gas van also has clear advantages in terms of environmental compatibility. By virtue of its propulsion unit, it produces 80 percent less nitrogen oxide than a diesel, and almost 20 percent less CO2 than a gasoline model (nearly 10 percent less CO2 than diesel). And the exhaust gases contain almost no soot particles.

High-level safety

The Zafira CNG is also ideally equipped when it comes to safety: the high-strength steel gas tanks and stainless steel gas pipes are safely located outside the impact zone. This was already confirmed by ADAC in a crash test conducted with the first Zafira CNG: “The gas tanks stored in a metal compartment remained in their original position during both frontal and side collisions, despite body deformation. They are therefore optimally protected against damage. The entire gas system stayed tightly sealed, also a result of the safety valves that automatically close on the tanks,” said the automobile club experts, summing up the test results. In addition, the results clearly showed that the risk of fire with natural gas vehicles is no higher than normal. This is also due to the fact that natural gas is much less flammable than gasoline or diesel, and in the highly unlikely event of a leak, it dissipates immediately. This means CNG vehicles can be parked in any underground garage. Like all Zafiras, the 1.6 CNG ecoFLEX also features the extensive and extremely effective SAFETEC safety system that earned the new Zafira the maximum rating of five stars for passenger protection in the Euro NCAP crash tests (European New Car Assessment Programme).

Unrestricted everyday suitability

The natural gas Zafira’s excellent efficiency and unrestricted everyday suitability is ensured by the innovative monovalentplus concept. The 1.6-liter CNG engine, which has an increased compression ratio for high efficiency, is designed to run on natural gas, biogas, or any mixture of the two. The unit has special pistons, valves and valve-seat inserts, as well as separate injection banks for natural gas and gasoline. In addition, the engine management system was optimized for natural gas operation. A 14‑liter gasoline reserve tank ensures continued mobility on routes without a natural gas filling station. Thanks to economical consumption and the four natural gas tanks’ capacity of 21 kilograms, the Zafira CNG has an operating range of around 530 kilometers.

Opel Combo 1.6 CNG ecoFLEX: Cargo volume up to 3200 liters

Available since June 2005, the Opel Combo 1.6 CNG is a spacious, multi-functional natural gas vehicle. With an average consumption of 4.9 kg of natural gas per 100 kilometers, the 69 kW/94 hp high-roof van is very economical and environmentally friendly. Accordingly, Opel awarded the car the ecoFLEX badge, which it gives to only the most economical and low emission variants. Tax and insurance ratings are at the same level as those of the gasoline unit. The Combo CNG’s top speed is 165 km/h and acceleration from zero to 100 km/h takes 15 seconds.

Thanks to the clever underfloor arrangement of the three gas tanks around the Combo's space-saving rear axle, the alternative propulsion requires no compromises in terms of practicality. Just like its conventionally powered counterparts, the compact Combo CNG offers up to 3050 liters cargo volume in its five-seat Combo, Edition, Arizona and Sport variants, while the panel van even offers a maximum 3200 liters. The tanks hold

17.5 kilograms or 108 liters of natural gas. Combined with a 14-liter gasoline reserve tank, this enables an operating range of over 500 kilometers. The Combo CNG features the same high safety standards as the gasoline entry-level version. The tanks that hold the natural gas compressed to 200 bar are tested before installation at a pressure of 300 bar. The high-strength steel tanks are protected by underbody shields and, together with the stainless steel gas pipes, are located outside the impact zone.

February 2006: Testing by TFH (Wildau Technical College) traffic logistics research group commissioned by the German Federal Environment Ministry uses the Combo CNG as an example to prove the outstanding efficiency of natural gas propulsion

April 2007: German automotive magazine “Auto Bild” posts the following conclusion from a multi-brand comparison of six different passenger car propulsion systems: “If you want to save money, go with the Zafira CNG”

August 2007: Zafira 1.6 CNG again named “Best seven-seater“ in VCD environmental list